Connecting Gmail calendar to Outlook is a popular request and unfortunately, it's not possible unless you use an add-in. However, if you only need a read-only calendar, you can add a Gmail calendar as an Internet Calendar and view your appointments (but not edit or add new appointments).
You need to use the Private ics link in Gmail and add it as an Internet Calendar in File, Account Settings, Internet Calendar.
Another option, if you use Outlook.com, is to subscribe the calendar in Outlook.com. The shared calendar syncs with the Outlook.com account. It's still going to be read-only, but avoids the occasional send and receive errors a subscribed calendar generates.
The Google Calendar Sync Utility utility will work with Outlook (all versions).
- Go to your Gmail calendar
- Move the mouse over your calendar name then click on the caret to the right of the calendar name to expand the menu. Choose Share this calendar
- Click the Calendar Details tab.
- Click the ICAL icon for the Private Address. If you choose the Public Address, you need to enable public access on the Share this calendar tab.
- Right-click on the URL and choose Copy.
- In Outlook, go to File, Account Settings, Internet Calendar tab.
- Click New.
- Paste the URL in the address field. It's no longer necessary to remove the S from the HTTPS URL, but if Outlook won't download or gives you an error, remove it.
- Click Add. Enter a friendly name for the calendar and return to Outlook.
The calendar will sync to Outlook but it is read-only. You can't add appointments in Outlook and have them sync up to the server. Updates made to the calendar online should sync down to Outlook hourly.
Subscribe to a Google Calendar Video Tutorial
This video shows the steps to get the iCalendar ICS URL from Google Calendar as well as add it to Outlook.
Additional articles on using Gmail with Outlook